[Patches] [ python-Patches-1232343 ] PyOS_Readline

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Patches item #1232343, was opened at 2005-07-04 15:03
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Category: Core (C code)
Group: Python 2.5
Status: Open
Resolution: None
Priority: 5
Submitted By: Lisandro Dalcin (dalcinl)
Assigned to: Nobody/Anonymous (nobody)
Summary: PyOS_Readline

Initial Comment:
Greg Lielens submitted some time ago a patch [id 955928] about
'PyOS_Readline()' behavior with non-interactive tty's. Basically,
there is no way to properly override 'PyOS_ReadlineFunctionPointer' 
as
'PyOS_Readline()' calls 'PyOS_StdioReadline()' when 'stdin' or
'stdout' are not tty's. A snippet of "Parser/myreadline.c":

...

if (!isatty (fileno (sys_stdin)) || !isatty (fileno (sys_stdout)))
        rv = PyOS_StdioReadline (sys_stdin, sys_stdout, prompt);
else
        rv = (*PyOS_ReadlineFunctionPointer)(sys_stdin, sys_stdout,
                                             prompt);
...

Greg Lielens is completely right about the problem, but his patch is
perhaps a bit crude, it also modifies "Python/bltinmodule.c" to solve
the same issue with 'raw_input'.

I think I have found a not so crude solution, and completely 
backward
compatible.  Basically, I moved 'isatty()' test from 'PyOS_Readline()'
in file "Parser/myreadline.c" to 'call_readline()' in file
"Modules/readline.c". In order to do that, I believe
'PyOS_StdioReadline' have to be added to file "Include/pythonrun.h".

All those changes will not affect in any way the behavior in
interactive sessions. Now 'PyOS_ReadlineFunctionPointer' can be
properly overrode and users of 'readline' module will not see any
change: in non-interactive tty's 'PyOS_StdioReadline()' will be called
anyway.  The problem in 'input' and 'raw_input' builtins remains, but
its solution is not so clear to me, I think this part should not be
touched right now.

This patch passes 'Lib/test/regrtest.py' (of course, all those tests
are non-interactive!). I use Python interpreter every day in the
standard way and also in MPI-parallelized interactive sessions with
this patch applied, and I never have any problem.

I send my patch obtained with 'cvs diff -c' from current sources.


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